Improvement in gilding, silvering



. UNITED STATES P TENT OFFICE.

DANIEL DAVIS, JR, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN G'ILDING, SILVERING, &.c., IN DEAD COLORS.

Specification forming part of Letters Patent No. 3,015, dated March 21, 1843.

To all whom it may concern: 7

Be it known that I, DANIEL DAVIS, Jr., of Boston, in the county of Sufi'olk and State of Massachusetts. have discovered a new Method or Process of Producing Dead Metallic Colors on Brass, Copper, Iron,Steel, and various other Metals, or of producing by galvanic agencyv metallic surfaces resembling what is termed in the arts dead-gilding; and I do hereby declare that the following is a full and exact description of the same, wherein Ihave set forth the nature and principles of my discovery, by which it may be distinguished from others of like character, together with such parts or combinations thereof as I claim and consider new.

The process of gilding upon clocks, lamps, and other ornamental metallic articles has generally heretofore been carried on through the agency of acids, the articles being dipped or suspended in the solution (which is heated during the operation) until the requisite color is produced. The deadening has been performed by several processes, generally during the operation of cleaning, by means of an acid known in the arts by the term (leading aqua fortis, or by a weak solution of nitrate of mercury applied to the articles previous to the gilding process. I

My improvement in the deadening of the gilding is applicable to that method b whit-h metals are coated or covered with meals by the operation of the galvanic battery, or that usually known in the arts by the term "electrotyping; and it consists, when brass or copper articles are to be gilded, in first depositing a thin coating of copper upon them, and next a layer of gold, or of the metal required upon the said coating of copper. The layer of copper first put on in connection with the gold or other metal afterward deposited produces a deadening of the latter in a most thorough and beautiful manner. Such part of the articles on which I-niay be desirous of producing a bright gold color or reflecting-surface may be burnished in the ordinary manner.

In order to produce the deadened metallic surface upon articles of iron or steel, it becomes necessary to prevent the local action of the acid solutions in which said articles are dipped and subjected to the action of the galvanic battery, the said local action'having hitherto prevented such metals from receiving the deposit of copper to that degree of perfection necessary. I have discovered that by adding cyanuret of potassium to the solution of sulphate of copper in which the article is immersed the acid of the solution is neutralized and the deposit of metal readily takes place upon any article of iron or steel. The article having thus received a coating of 00p per from the neutralized solution it may next have a thicker coating of copper applied by,

potassium in order to prevent the efl'ects of local act on, then precipitating cooper from the sulphate, and lastly gold or silver thereon, the whole process being substantially as hereinhet'ore set forth.

in testimony that the foregoing is a true description of my said discovery and improve merits I have. hereto set my signature this 26th day of November, in the year 1842.

DANIEL DAVIS, JR.

Witnesses: I

R, H. EDDY, E. LINcoLN, Jr. 

